Metal strap twisting machine

ABSTRACT

A metal strap twisting machine comprising first and second longitudinally aligned carrier members, a transversely extending wheel intermediate said carrier members, a strap holder detachably secured in said wheel, an end holder mounted on each of said carrier members and adapted to secure a selected portion of said strap, a plurality of members mounted on each of said carrier members adapted to position said end holder and said strap, means to automatically stop said wheel after a predetermined number of revolutions, and means to vary the twisting force applied by said wheel to said strap.

Dawson Mar. 12, 1974 METAL STRAP TWISTING MACHINE Inventor: James R. Dawson, 8621 N. New

Braunfel, San Antonio, Tex. 78217 [22] Filed: Apr. 11, 1972 [21] Appl. No.: 243,002

[52] U .S.C1. .I....I... ..L".'."I..."...I7i729 [51] Int. Cl. ..B2ld 11/14 [58] Field of Search 72/299, 371, 112, 125, 72/302, 305; 140/118, 119, 149

[56] References Cited UNITED STATES PATENTS 2,616,478 11/1952 DAva'ucourt 140/149 3,465,743 9/1969 Gilmore et al..;. 140/149 2,375,835 5/1945 Anderson 140/120 404,934 6/1889 Runyon 140/120 2,603,269 7/1952 Long; 72/299 8,032 l/1878 Shortau i 72/299 983,896 2/1911 -Hartel et al 72/299 FOREIGN PATENTSlOR APPLICATIONS 837,541 6/1960 Great Britain 72/299 Primary ExaminerCharles W. Lanham Assistant Examiner-M. J. Keenan Attorney, Agent, or Firm.lohn C. Stahl [57] ABSTRACT A metal strap twisting machine comprising first and second longitudinally aligned carrier members, a transversely extending wheel intermediate said carrier members, a strap holder detachably secured in said wheel, an end holder mounted on each of said carrier members and adapted to secure a selected portion of said strap, a plurality of members mounted on each of said carrier members adapted to position said end holder and said strap, means to automatically stop said wheel after a predetermined 'number -of'revolutions, and means to vary the twisting force applied by said wheel to said strap.

7 Claims, 11 Drawing Figures PATENIEDHAR Z I91 3L796L083 SHEET 5 BF 6 FIG. 6 FIG. 7

METAL STRAP TWISTING MACHINE BACKGROUND or THE INVENTION In the art of metal working, it is often desirable to provide a strap or bar of metal with a spiral or convolution for either decorative or utilitarian purposes.

Heretofor e hand operated devices have been utilized for such purposes, however, these devices are unable to provide uniformity of the spiral or various leads or pitch within a specified length, or to achieve mass production of precision parts.

SUMMARY OF THE INVENTION The primary object of the invention is the provision of a strap twisting machine which provides reproducible and precision spirals of desired and uniform pitch in a piece'of metal strap.

Another object is the provision of such a strap twisting machine wherein the twist or convolution imparted to the metal strap is confined to a predetermined length along the length thereof. 7

Still another object is to provide such a machine wherein the flat terminal sections, and the flat sections intermediate any desired number of twisted or convoluted sections, lie in the same longitudinal plane.

A further object is to provide such a metal strap twisting machine including means to vary the force applied to such strap dependent upon the number of spirals or convolutions to be provided in the section or sections undergoing twisting.

A final object is to provide such a strap twisting machine which is relatively simple to operate, and requires little or maintenance or repair over extended periods of time.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a top plan view of the metal strap twisting machine of the subject invention.

FIG. 2 is a view taken on the lines 22 of FIG. 1, looking in the direction of the arrows, with the medial portion partially broken away.

FIG. 3 is an enlarged, vertical sectional view, transverse to the longitudinal axis, taken laterally of the wheel of the subject invention. 1

FIG. 4 is an enlarged, front elevational view of the vertically adjustable counting and stop means of the subject invention.

FIG. 5 is an enlarged, rear elevational view, showing the support and activating means for the counting and stop means of FIG. 4.

FIG. 6 is a greatly enlarged view, taken on the lines 6-6 of FIG. 4, looking in the direction of the arrows.

FIG. 7 is a greatly enlarged view, taken on the lines 7-7 of FIG. 6, looking in the direction of the arrows.

FIG. 8 is an enlarged, front elevational view of one embodiment of strap holderof the subject invention.

FIG. 9 is an enlarged view, taken on the lines 99 of FIG. 8, looking in the direction of the arrows.

FIG. 10 is a fragmentary, enlarged, front elevational view of the lower portion of the strap holder, and securing and raising means therefor! FIG. II is a greatly enlarged, perspective view, partly broken away, showing the several members positioned on one side of the wheel and utilized during the twisting operation.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION and coextensive in length therewith, are fixedly secured to the respective bed plates.

Transversely extending wheel 26, mounted intermediate carrier members 24-25, comprises longitudinally spaced hubs 27 spokes 28 radiating therefrom, and rim 29 with circumferential groove 30 therein. Bearings 31 are press fitted or otherwise fixedly secured in each hub; coaxial, split hollow axles 32 are fixedly secured to members 24-25 as by brackets 33 or the like with the innermost end of each hub at least partially journaled in the adjacent bearing. Rearwardly of wheel 26 pulley 34 of desired diameter is carried on shaft 35, each end of said shaft is journaled in a pillow block 36 mounted on plates 22-23, respectively. Motor 37, desirably mounted on plate 23, drives pulley 34 by means of belt 38. A l 10 volt, alternating current source .electrically connects to motor 37 with a master switch (not shown) desirably mounted on frame 21 or an adjacent supporting surface whereby said motor may be operated. Pulley39, aligned with wheel 26 and secured to shaft 35, carries belt 40 which rides in a relatively loose fit in groove 30 in the rim of wheel 26.

As best seen in FIG. 3 of the drawings, air cylinder 41 is secured intermediate and downwardly of plates 22-23 by means of vertically spaced and longitudinally extending frame members 2la-2lb; a regulator controlled air source (not shown) providing from 40-60 p.s.i. connects to a double-acting solenoid 42 mounted on frame 21 and thence to said air cylinder in a conventional manner. Shaft 43 of air cylinder 41 carries clevis 44 with pulley 45 mounted therein, said pulley is adapted to bear against and tension belt 40 heretofore mentioned. Brake shoe 46 conforms in curvature to wheel 26; one end of said brake shoe is secured to frame member 21c by hinge 47. Plate 48, which terminates laterally of shoe 46, is fixedly secured to the undersurface of said shoe in proximity to the remote end thereof. Brake lining 49 is conventionally secured to the upper surface of shoe 46 while stud 50, secured to the undersurface'of plate 48, accommodates one end of spring 51 hereinafter to be more fully described.

Horizontally and longitudinally extending frame member 21d includes longitudinally spaced and vertically extending lugs 21e secured thereto with tubular member 52, the major axis of which is in the plane of wheel 26, pivotally mounted therebetween. Tubular member 53 is carried in telescoping relationship within member 52 with the rear end of member 53 connected by means of hinge 54 to clevis 44. Laterally spaced and forwardly extending lugs 55 are secured to member.52; machine screws 56, threaded into said lugs, are adapted to bear against the upper surface of plate 48 laterally of shoe 46. Forwardly extending lug 21 f on frame member 21d accommodates screw 57 with jam nuts 58 threaded thereon; the lower end of spring 51 is carried by screw 57 and the braking force applied by lining 49 against wheel 26 is adjusted thereby. It is understood that upon activation of air cylinder 41, shaft 43 extends whereby tubular members 52-53 remotely connected thereto are rotated in a counterclockwise direction (see FIG. 3); at such time, brake lining 49 is retracted from wheel 26 and pulley 45, tensioning belt 40, drives wheel 26 from -30 r.p.m. in a'clockwise direction. When shaft 43 of air cylinder 41 is retracted, the tensioning force on belt is released and wheel 26 is not driven; simultaneously, tubular members 52-53 rotate in a clockwise direction whereby spring 51 forces brake shoe 46 upwardly and brake lining 49 frictionally engages and prevents rotation of wheel 26.

Referring now to FIGS. 8-10 of the drawings, there is shown one embodiment of strap holder 59 adapted to be detachably secured in wheel 26. More particularly, a vertically and transversely extending member 60 (see FIG. 3) is secured to the inner surface of each hub 27 intermediate adjacent spokes 28 with cross member 61 fixedly secured to the outer ends thereof. Aligned, radially extending and inwardly opening slots 62 are provided in each member 60. Holder 59 comprises horizontally extending, vertically spaced straps 63-64 with a medial, vertically extending strap 65 fixedly secured thereto; rectangular recesses 66 are provided in each side strap 65 downwardly of horizontal strap 64 with the lower end thereof preferably beveled, indicated by reference numeral 67. Spacers 68 corresponding to the thickness of the strap to be twisted, are placed on one side of straps 63-64, and vertically extending angles 69-70 69a-70a detachably secured in proximity to each end thereof. Those portions of straps 63-64 laterally of said angles insert into slots 62 heretofore described. A rectangular slot 71 is provided in the medial portion of cross member 61 to accommodate the lower portion of strap 65. It is understood that the horizontal distance between the most lateral surfaces of angles 69-70 and the corresponding inwardly-opening angles 69a-70a on the opposite end of said holder determines the length of the flat intermediate the twisted or convoluted portions in a strap. In the preferred embodiment of the invention, the distance between angles 69-70 and 69a-70a, respectively, ranges from l-4 inches, desirably in wholenumbers.

As best seen in FIG. 3 of the drawings, angularly extending lug 72 is secured to the medial, lower surface of cross member 61. An elongated strap 73, adapted to insert into recess 66, is remotely connected to lug 72. More specifically, machine screw 74 carries spring 75 which is adjusted to bear against strap 73, said screw also carries washer 76 and is threaded into lug 72. Locking bar 77 hingedly connects to a downwardly depending lug 78 on cross member 61. The medial portion of bar 77 bears against the undersurface of strap 73 whereas the remote end of said bar passes through rectangular, radially extending slot 79 in vertically and transversely extending plate 80 which is fixedly secured to cross member 61.

Referring now to FIG. 2 of the drawings, there is shown means to raise strap holder 59 to engage a selected portion of strap metal or the like prior to twisting. More specifically, rocker arm 81 is pivotally connected to frame member 21c; one end of arm 81 pivotally connects to the upper end of an elongated strap 82 with a perpendicularly outwardly extending foot pedal 83 secured to the lower end thereof. The opposite end of arm 81 pivotally connects to one end of vertically extending strap 84; said strap passes through bracket 85 and is fixedly secured to a transversely extending curved member 86 (see FIG. 3). Pressure applied to pedal 83 causes member 86. to be forced upwardly against the outer'end of bar 77, raising the same; continued pressure forces strap holder 59 upwardly until stopped by the upper edge of strap 73 butting the lower surface of cross member 61. A piece of metal strap, inserted through axles 32, is passed downwardly between angles 69-70 69a-70a; rotation of wheel 26 approximately 15 from the vertical binds said. strap after which foot pedal 83 may be released.

There is shown in FIGS. 1 and 11 of the drawings a typical embodiment of each of the members, indicated by reference numerals 87-90, positioned on carrier members 24-25, respectively. For purposes of convenience only, those members positioned on member 24 on the left-hand side of wheel 26 will be described in detail; it is understood that the corresponding members positioned on member 25 on the right-hand side of wheel 26. are similar in construction and mirror images thereto.

End holder 87 includes base 91 which slides on the upper flange 92 of member 24; downwardly depending and return flanges 93-94, respectively, on base 91 engage the outermost portions of flange 92. Plate 95, fixedly secured to base 91, terminates outwardly in transversely extending bevel 96 with hinge 97 secured adjacent thereto; hasp 98 of said hinge terminates inwardly of base 91 in a perpendicularly extending plate 99 provided with a vertically and downwardly opening slot 100 extending in the medial plane of the respective carrier members. In operative position, plate 99 is rotated downwardly at which time hasp 98 rests on the upper surface of plate 95 with the lower edge of plate 99 spaced slightly above the upper surface of flange 92.

Stops 101-103 each include a hinge 104 secured in proximity to the rear edge of base 91; rotatable and transversely extending arm 105 terminates inwardly in a vertical plate 106 the lower edge of which is adapted to bear against the upper surface of base 91 in operative position; when not in use, each of said stops is maintained in elevated condition away from the working area. It is understood that plates 106a-106b are secured in like manner to stops 102-103, respectively;

stops 101-103 are a predetermined distance rearwardly of plate 99 whereby the user may provide an exact, predetermined terminal portion on each twisted strap.

Members 88-90 heretofore mentioned are carried on a tubular member 107 the foremost edge of which is vertically aligned with and slightly below the corresponding edge of each carrier member. Strap 108 includes an inwardly extending plug 109 or the like adapted to insert into each end of member 107; said strap is secured rearwardly to a selected portion of said carrier member in a conventional manner.

Fore-stop 88 includes tubular member 110 carried exteriorly of tubular member 107 with a set screw 111 threaded therein and adapted to bear against member 107. Arm 112 is secured as by hinge 113 to the front surface of member 1 10; perpendicularly extending segment 114 of said arm is adapted to lie flat on the upper surface of flange 92. Bracket 115, housing a longitudinally and outwardly extending spring biased pin 116, is secured to segment 114 in a conventional manner. In use, fore-stop 88 is secured at a desired position on member 24 after which plate 99 of end holder 87 is butted against the end of pin 116. During the twisting operation the strap to be twisted, secured at one end in slot 100 in plate 99, shortens; such construction permits end holder 87 to be pulled inwardly against the force exerted by spring biased pin 116 to compensate for such shortening of the strap.

Rear stop 89 is substantially similar in construction to fore-stop 88. Segment 114a terminates inwardly in a perpendicularly inwardly extending plate 117 adapted to lie on the upper surface of flange 92. It is understood that said rear stop 89 is fixedly secured in a desired position on tubular member 107 after which the rear end of holder 87 is butted against the innermost end of said plate 117.

Stop 90, also similar in construction to fore-stop 88, partially includes segment 114b to which vertically extending plate 118 is secured. One end of a metal strap may be butted against plate 118 to accurately position the same preparatory to twisting.

It is understood that members 8890 are positioned at prescribed positions on the said carrier members after which any of said members may be rotated forwardly away from the working area and end holder 87 slid along said carrier member in either direction; during the twisting operation, members 88-90 may be rotated upwardly over flange 92 whereby holder 87 or a piece of strap metal may be exactly positioned preparatory to the twisting steps hereinafter to be described in detail.

Referring now to FIGS. 4-7 of the drawings, there is shown counting and stop means whereby after a desired number of complete or half turns are provided in a selected portion of strap metal, in either a right-hand and/or left-hand direction, machine is stopped preparatory to subsequent operation. More specifically, a longitudinally extending angle comprising flanges ll9120 is conventionally secured to bed plate 22 rearwardly of carrier member 24. Horizontal flange 119 is desirably elevated relative to the upper surface of plate 22 or a recess 121 provided in plate 22 below at least a portion of flange 119. The approximate medial portion of vertically extending strap 122 is butt welded or otherwise fixedly secured to the inner end of flange 120, said strap 122 terminates substantially below bed plate 22, Vertically extending strap 123, greater in length than strap 122 and transversely aligned therewith, is adjustably secured thereto by means of vertically spaced, horizontally extending straps l24-l25 fixedly secured to the rear surface of strap 122 with flanges 126-127 passing laterally and forwardly, respectively, of the inner edge portions of strap 123. Lug 128 is fixedly secured to the front surface of strap 121 intermediate straps 124-125 and at least partially overlies the frontal, edge portions of strap 123.

As best seen in FIG. 4, a six-pointed star counter 129 comprising points 129a129f is rotatably mounted in the medial portion of strap'123. Rearwardly extending pins 130a -130b are secured to points 129a,129d respectively. More specifically, forwardly extending stud 131, fixedly secured to strap 123, carries spacer 132 and an elongated sleeve 133 with disc 134 and gear 135 secured thereto. Star counter 129, terminating rearwardly in collar 136, is carried on said sleeve;

points 129a-129f on said counter are aligned with the corresponding teeth on gear and said counter adjustably positioned and secured to said sleeve by means of set screw 137 in collar 136. Spring 138, detachably secured at one end to strap 123, carries pawl 139 on the lower end which is adapted to insert intermediate the teeth on said gear whereby points 129a-129f are exactly positioned prior to the start of each cycle; the rear surface of said pawl also bears against the foremost surface of disc 134, maintaining the counting means thus formed on stud 131.

Arcuate segment 140 (see FIG. 3), ninety degrees forwardly of strap holder 59 and secured intermediate adjacent spokes 28, includes an outwardly extending striker arm 141 adapted to bear against points 129a-l29f on counter 129 thereby rotating the same.

Referring now to FIG. I, handle 142 terminates inwardly in rod 143 which is passed through the web of carrier member 24 and connects by means of universal joint 144 to one end of rearwardly extending rod 145. A universal joint 146 on the remote end of rod includes pin 147 adapted to insert into recess 148 in the foremost end of sleeve 133 whereby the user may conveniently regulate the number of turns or half turns to be provided in a section of strap metal merely by rotating handle 142.

Arm 149 is pivotally mounted on strap 123 downwardly of stud 131. Machine screw 150, carrying washers 151 laterally of arm 149, and also carrying spring 152, is threaded into said strap. The upper end of arm 149 is bevelled, indicated by reference numeral 153, with pins l30a-130b on counter 129 adapted to bear against said bevelled portion and rotate said arm. One end of spring 154 is conventionally secured to strap 123 downwardly of screw with the remote end adapted to pass outwardly of the lower portion of said arm, returning the same to its original position.

Microswitch 155, including movable arm 156, is fixedly secured in proximity to the lower end of strap 123. Upon rotation, the lower end of arm 149 bears against arm 156 of said microswitch, closing the contacts therein; solenoid 42 electrically connected thereto is energized and the air source connected to air cylinder 41 causes shaft 43 to retract at which time wheel 26 is stopped in the manner heretofore described and the twisting cycle is completed.

It is understood that the force required to twist a piece of strap metal varies directly as the length of the section or sections of strap to be twisted and the numbar of twists provided therein; accordingly, means are provided whereby the force applied to a piece of strap metal may be varied. As shown in FIGS. 1 and 10 of the drawings, an arcuate, externally notched member 157 is secured at each end to a selected portion of carrier member 24. As heretofore mentioned, recess 121 is provided in the upper surface of bed plate 22, said recess at least partially passing under carrier member 24 and flange 119, respectively. Rotatable arm 1S8, lying in recess 121, is pivotally connected to lug 159 fixedly secured to flange 119; arm 158 terminates forwardly in' a spring loaded pin 160 adapted to insert into a selected notch in member 157.

Vertical support 161 (see FIG. 10) is fixedly secured to the rear surface of flange 120. A bell crank 162 comprising arms l63-164 pivotally connects in proximity to the upper end of support 161. Link 165 connects to the lower end of arms 158 and 163, respectively. Link 166 connects to the remote end of arm 164 and to strap 123 whereby upon rotation of arm 158 from left to right the said strap 123 is lowered. When strap 123 is in the uppermost or raised position, it is evident that striker arm 141 on wheel 26 moves through a lesser arc prior to abutting a selected point on counter 129. As strap 123 is lowered to the full extent, however, arm 141 on wheel 26 travels through a greater arc prior to butting a selected point on said counter whereby power is applied to the said wheel 26 for a relatively greater period of time.

Normally open start and stop switches 167-168 are desirably secured to a selected portion of frame 21. It is understood that the master switch heretofore mentioned not only activates motor but also provides power across the terminals of switches 167,168. Start switch 167 energizes solenoid 42 whereby the compressed air source is applied to air cylinder 41 causing shaft 43 to extend; at such time, pulley 45 tensions belt 40 and wheel 26 is driven. Stop switch 168, also connecting to solenoid 42, causes cylinder 41 to exhaust its air supply whereby shaft 43 retracts and wheel 26 stops rotating.

The operator inserts a piece of strap metal, of desired length, through axles 32 of wheel 26 and normally butts one end of said strap against stop 90 to accurately position the same. As heretofore mentioned, members 8790 are exactly positioned on the respective carrier members in accordance with a prepared schedule, determined primarily by the number of spirals or twists, length of each section to be twisted, and number of half turns. or complete turns in each section. The operator then secures the medial portion of said strap in holder 59 after which end holders 87, on one or both sides of wheel 26, are positioned in accordance with said schedule; said strap is then secured outwardly in slot 100 of said end holders with the inner face of each respective plate 99 butted against pin 116. It is understood that the length of each spiral or convolution is determined by the distance between the most lateral side of angles 69-70 and 69a-70a and plate 99 of the end holder 87 in which said strap is secured laterally.

To provide any desired number of half turns in the finished product, strap holder 59 is vertically aligned and opens downwardly as shown in FIG. 3; for complete turns, said strap holder is vertically aligned and opens upwardly as illustrated in FIG. 8 of the drawings. Handle 142 is then rotated whereby pins 130a-l30b on counter 129 are so positioned relative to striker arm 141 that the required number of complete or half turns will occur at the time that the electrical contacts in microswitch 155 are closed whereby wheel 26 is stopped. If the strap to be twisted requires an exception number of spirals or convolutions, the position of bar 158 may be regulated in the manner heretofore illustrated and described in connection with FIGS. 47 of the drawings.

After such preliminary steps are completed, switch 167 is closed and wheel 26 is driven at approximately 25 rpm. Normally, microswitch 155 stops wheel 26 after completion of the twisting cycle; however, if required, stop switch 168 instantaneously stops wheel 26 from rotating.

At the completion of each cycle, strap holder 59 drops downwardly and the operator may either remove the twisted strap or reposition the same whereby any desired number of left-hand and/or right-hand spirals or convolutions are provided, dependent upon which end holder is utilized. Each end of said strap may finally be butted against a selected plate 106, 106a or 106b whereby a predetermined terminal portion of l, 1.5 or 2 inches, respectively, is provided outwardly of the last spiral or twisted section.

It is understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is: 1. A machine adapted to twist a piece of strap metal comprising first and second longitudinally extending and interiorly spaced carrier members,

a wheel mounted between said carrier members,

a strap holder secured in said wheel,

at least one end holder carried on at least one of said carrier members laterally of said wheel and adapted to secure a selected portion of said strap,

means to drive said wheel,

fluid activated clutch means coacting with said wheel, and

counting means coacting with said clutch means to stop said wheel after a predetermined number of revolutions.

2. The invention of claim 1 further including means coacting with said counting means to vary the force exerted by said machine on said strap.

3. The invention of claim 1 further including means to selectively position said end holder on said carrier members.

4. A machine adapted to twist a piece of strap metal comprising first and second longitudinally extending and interiorly spaced carrier members,

a transversely extending wheel mounted between said firstand second carrier members,

a strap holder detachably secured in said wheel,

at least one end holder carried on each of said carrier members and adapted to secure a selected portion of said strap,

drive means for said wheel,

fluid activated clutch means coacting with said drive means,

counting means coacting with said clutch means to stop said drive means after a predetermined number of revolutions,

means on said wheel adapted to activate said counting means, and

means coacting with said counting means to vary the force applied to said piece of strap.

5. The inventon 'of claim 4 wherein said wheel includes a hollow axle, said strap inserted through said axle and engaged by said strap holder.

6. The invention of claim 4 wherein said wheel includes a rim, said drive means remotely connected to said rim.

7. The invention of claim 4 wherein said counting means comprises a six-pointed star, and at least one rearwardly extending pin secured to said star adapted to coact with said means on said wheel to activate said counting means. 

1. A machine adapted to twist a piece of strap metal comprising first and second longitudinally extending and interiorly spaced carrier members, a wheel mounted between said carrier members, a strap holder secured in said wheel, at least one end holder carried on at least one of said carrier members laterally of said wheel and adapted to secure a selected portion of said strap, means to drive said wheel, fluid activated clutch means coacting with said wheel, and counting means coacting with said clutch means to stop said wheel after a predetermined number of revolutions.
 2. The invention of claim 1 further including means coacting with said counting means to vary the force exerted by said machine on said strap.
 3. The invention of claim 1 further including means to selectively position said end holder on said carrier members.
 4. A machine adapted to twist a piece of strap metal comprising first and second longitudinally extending and interiorly spaced carrier members, a transversely extending wheel mounted between said first and second carrier members, a strap holder detachably secured in said wheel, at least one end holder carried on each of said carrier members and adapted to secure a selected portion of said strap, drive means for said wheel, fluid activated clutch means coacting with said drive means, counting means coacting with said clutch means to stop said drive means after a predetermined number of revolutions, means on said wheel adapted to activate said counting means, and means coacting with said counting means to vary the force applied to said piece of strap.
 5. The inventon of claim 4 wherein said wheel includes a hollow axle, said strap inserted through said axle and engaged by said strap holder.
 6. The invention of claim 4 wherein said wheel includes a rim, said drive means remotely connected to said rim.
 7. The invention of claim 4 wherein said counting means comprises a six-pointed star, and at least one rearwardly extending pin secured to said star adapted to coact With said means on said wheel to activate said counting means. 